Should Mass. homeowners be allowed to build extra apartments onto their houses?

Even as real estate prices escalate, many Greater Boston communities still ban or restrict homeowners from adding “in-law,” or accessory apartments.

The apartments, sometimes put in as part of an addition, can provide space for elderly parents or an adult child just getting started on a career, supporters say.

Now two major real estate groups are pushing a proposal that would give a green light to accessory apartments in cities and towns across the state.

And Newton Mayor Setti Warren is joining the effort as well, with a proposal to provide more options for homeowners considering in-law apartments.

“We have heard stories that in the suburbs it has been a problem,” said Greg Vasil, executive director of the Greater Boston Real Estate Board, one of the backers of the statewide proposal. “A lot of towns won’t allow it.”

The real estate board is teaming up with the Massachusetts Association of Realtors on the accessory apartment proposal, with Rep. Kevin Honan (D-Brighton), the House’s housing committee chair, sponsoring the bill.

The proposal would require towns across the state to allow accessory apartments in all areas zoned for single-family homes. The units can be either built into the house or in an attached structure.

Vasil argues that many of the restrictions placed on in-law apartments by local communities are outdated and should change to meet the needs of the current housing market, where demand for housing of all types far outstrips the supply of available homes and rentals.

“We have to adapt these rules to the current issues society is dealing with,” Vasil said.

The proposal is needed now more than ever, Vasil contends, as it provides families with an alternative to paying for expensive assisted-living and retirement complexes when their aged parents need extra help.

In other cases, the adult children or other family members may buy the house, and the parents can move into the in-law apartment. That too can provide another option for young families and buyers struggling with the state’s high housing costs, he said.

“The legislation... is antithetical to the whole idea of local zoning”

Still, local officials have had mixed feelings when it comes to accessory apartments.

The Massachusetts Municipal Association, which represents cities and towns across the state, vowed to fight the accessory housing bill.

The bill would undercut the authority of local officials and residents to make decisions on zoning rules, said Geoffrey Beckwith, executive director of the Massachusetts Municipal Association, who blasted the proposal as “wrong-headed.”

“The legislation would take a one size fits all approach to every community and every neighborhood in every part of Massachusetts,” Beckwith said. “That is antithetical to the whole idea of local zoning.”

But some communities are changing their tune, like Newton, where Mayor Warren announced plans to explore more flexible rules when it comes to in-law apartments.

As it stands now, most homeowners seeking to put in an in-law apartment must go through the special permit process, an expensive undertaking that can require hiring a lawyer and producing extensive design documents, said James Freas, acting director of Newton’s planning department.

Allowing accessory apartments, among other advantages, could give elderly homeowners struggling to stay in their homes extra rental income.

By 2030, nearly a quarter of Newton residents will be senior citizens, up from 15 percent now, Freas noted.

In a first step, city officials recently reduced the minimum size of an accessory apartment from 400 square feet to 250 square feet. Newton officials plan to start hammering out the details of the proposal this summer.

“For seniors, being able to put an accessory apartment in their existing house may be the thing that allows them to stay in their homes and stay in Newton,” Freas said. “The bottom line is that this opens up options for seniors who want to stay in Newton.”